Make sure the MAP plugs are secure when they're stacked. Do you get excessive smoke when accelerating from a stop or during low throttle conditions while stacked and getting this code? If the truck is running ok and isn't smoking like it would if the MAP was unplugged then it's probably ok, just a gremlin. You could try cleaning the MAP and its contacts but I'm not sure if that would help.
2001.5, 4x4, NV4500, Adrenaline/Pulse, Super B, stage 5 jammers, walbro, 4" to 5" miters, 2" Skyjacker, 315 BFGs, valair 13" OFe, tunes by Alpine and JL.